Title:	A search for long-time-scale, low-frequency radio transients
Authors:	Murphy, Tara Dwarakanath, K.S. +25 Co-authors
Keywords:	active radio continuum
Issue Date:	Apr-2017
Publisher:	Oxford University Press for the Royal Astronomical Society
Citation:	Monthly Notices of the Royal Astronomical Society, 2017, Vol. 466, p1944-1953
Abstract:	We present a search for transient and highly variable sources at low radio frequencies (150–200 MHz) that explores long time-scales of 1–3 yr. We conducted this search by comparing the TIFR GMRT Sky Survey Alternative Data Release 1 (TGSS ADR1) and the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey catalogues. To account for the different completeness thresholds in the individual surveys, we searched for compact GLEAM sources above a flux density limit of 100 mJy that were not present in the TGSS ADR1; and also for compact TGSS ADR1 sources above a flux density limit of 200 mJy that had no counterpart in GLEAM. From a total sample of 234 333 GLEAM sources and 275 612 TGSS ADR1 sources in the overlap region between the two surveys, there were 99 658 GLEAM sources and 38 978 TGSS ADR sources that passed our flux density cut-off and compactness criteria. Analysis of these sources resulted in three candidate transient sources. Further analysis ruled out two candidates as imaging artefacts. We analyse the third candidate and show it is likely to be real, with a flux density of 182 ± 26 mJy at 147.5 MHz. This gives a transient surface density of ρ = (6.2 ± 6) × 10−5 deg−2. We present initial follow-up observations and discuss possible causes for this candidate. The small number of spurious sources from this search demonstrates the high reliability of these two new low-frequency radio catalogues.
Description:	Open Access
URI:	http://hdl.handle.net/2289/6716
ISSN:	0035-8711 1365-2966 - (online)
Alternative Location:	http://adsabs.harvard.edu/abs/2017MNRAS.466.1944M http://arxiv.org/abs/1611.08354 http://dx.doi.org/10.1093/mnras/stw3087
Copyright:	2017 The authors & the Royal Astronomical Society
Appears in Collections:	Research Papers (A&A)

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